The United States is the issuer of dollars. In the financial concept, as long as the US dollar is the main settlement currency of international trade, the US foreign exchange reserves will always be zero. Foreign exchange reserves refer to foreign convertible currencies held by a country's authorities and their means of payment.

In the period when the United States was the main settlement currency of international trade, according to the definition, the foreign exchange reserves of the United States refers to the currency held by the American authorities that can be converted into the currency issued by the United States. The currency issued by the United States is US dollars, so none of the currency issued by the US authorities can be converted into US dollars, that is, its foreign exchange reserves are zero. Other countries, such as China and China, hold US dollars as foreign exchange reserves, which can be converted into RMB issued by China authorities.